Abstract: Surface impedance boundary conditions (SIBCs) of high order of approximations basd on the Rytov method are introduced and implemented in the A-f finite element formulation. With first order elements, only first and second order approximations for the surface impedance are possible. Third order SIBCs require second order (or higher) finite elements. The order of approximation is not limited but only orders up to three are practical and useful. The method was implemented in an existing FEM code and results are shown to validate its use and accuracy.
Keywords: Surface impedance boundary conditions; finite element analysis; finite element formulations.